Baseball Specific Stretching, Part 2: Crossover Symmetry Cuff Stretching (CS²)
Written By Jim Moran, PT, Shoulder Specialist

Over the course of a playing career, the throwing shoulder undergoes adaptive changes as a result of the extraordinary forces produced during the throwing motion. These transformations include changes to muscles, ligaments and even the bones.

The most significant adaptation that occurs to throwing shoulder is called Humeral Retroversion. The high torque created from the late cocking, early acceleration phase of the throwing motion is strong enough to cause a remodeling at the growth plate in the humerus, in which the bone pivots into external rotation. The morphing of the bone allows the throwing arm to externally rotate approximately 10 degrees further back than the non-throwing arm. On the flip side, humeral retroversion causes the throwing arm to lose about 10 degrees of internal rotation.

The second adaptive change occurs to the ligaments of the shoulder capsule. The anterior or front side of the shoulder capsule is progressively loosened throughout a throwing athletes playing career. This also contributes to the increase in external rotation which is demonstrated in the late cocking phase, early acceleration phase of the pitcher's delivery.

Finally, the third adaptive change that occurs as a result of throwing is tightness in the posterior rotator cuff muscles. The Infraspinatus and teres minor play a vital role in decelerating the arm during the throwing motion. As a result of repeatedly decelerating the arm, these muscles undergo repetitive micro trauma followed by a healing response that tightens the posterior cuff, which increases the risk of injury unless proactively managed with proper arm care.

These three factors contribute to shifting the range of motion of the dominant shoulder into external rotation while reducing the amount of range into internal rotation when compared to the non-dominate side. This creates a paradox whereby the adaptations may disrupt the biomechanics of the shoulder while simultaneously improving the mechanical advantage enabling the athlete to throw with greater velocity.

Why do throwing athletes need to stretch their dominant shoulder?

Properly addressing posterior shoulder tightness in throwing athletes will increase range of motion and decrease the risk of injury. Studies have shown that if Glenohumeral Internal Rotation Deficit (GIRD), which is the difference between the internal rotation of the dominant versus non-dominant arm, is greater than 20 degrees , then throwing related injuries are more likely to occur. The humeral head can migrate superiorly and posteriorly in the pear shaped socket when the posterior cuff muscles are tight, potentially leading to a SLAP lesion (labral tear).

The Crossover Symmetry Cuff Stretching (CS²) is a quick and effective way to stretch the posterior cuff and regain loss range of motion into internal rotation. The routine takes less than two minutes and combines the most effective stretches for the posterior shoulder with the added benefit of mechanical traction to aid in joint decompression. The CS² promotes healthy shoulder range of motion and should be used in conjunction with the Crossover Symmetry rotator cuff and scapular strengthening system for superior arm care.

Stretches To Avoid
Stretching Into External Rotation

• Having non medical professionals torque on your arm into external rotation is dangerous because players and coaches commonly get too aggressive with this stretch
• Sport itself stretches shoulder sufficiently into external rotation
• Can negatively affect the stability of the shoulder
• Should only be performed by a medical professional

Sleeper Stretch

• Sleeper stretch is intended to stretch the posterior capsule which are the ligaments that connect the ball and socket. Most throwing athletes are not tight in the posterior capsule, it is the posterior cuff muscles which are tight and need to be stretched.
• Puts the shoulder into an impinging position
• Players get too aggressive with this stretch as well
• Should only be performed if prescribed by a medical professional

Crossover Symmetry Cuff Stretching (CS²)
Players should not perform this stretching routine if any of the following apply:

• Youth under the age of 14. They need to focus on stability rather than mobility.
• Previous dislocation of the shoulder with residual instability
• Diagnosed by a medical professional with instability of the shoulder
• If you are double jointed or extremely flexible (this can be determined using the Beighton Scale)

Guidelines

• Complete the CS² daily on the field following a dynamic warm-up
• Should be done prior to your rotator cuff and scapular activation phase
• Only stretch your throwing shoulder. The adaptive changes only occur to the dominant shoulder.
• Resistance: Blue for "elite" college athletes, Red for "athletic" high school athletes
• Clip the Crossover Cords at eye level
• Light intensity with a focus on relaxing the posterior cuff muscles rather than aggressively stretching them

Crossover Symmetry Cuff Stretching (CS²)